This invention relates to an auto choke device for an internal combustion engine and more particularly to an improved automatic choke device having a manual override that is particularly adapted for use with engines used in outboard motors or the like.
Typically engines incorporate some form of cold starting and cold running enrichment mechanism in their induction system for providing enrichment for starting and running under these conditions. One typical form of enrichment device comprises a choke valve that is positioned in the induction passage and which is moved to a closed position at low temperatures in order to provide enrichment for starting and running until the engine warms up. It is typically the practice to employ an automatic operator for the choke valve so that it will be automatically positioned in response to temperature variations so as to avoid the necessity for operator control. One form of automatic choke operator incorporates a biasing spring that will tend to bias the choke valve to one of its positions (either open or closed). A thermally responsive element cooperates with the choke valve and the spring so as to determine the actual choke valve position. Although such automatic operators obviously have a number of advantages, they can present problems when the automatic operator becomes disabled either permanently or temporarily.
Typically an automatic choke mechanism will either fail by holding the choke valve in its fully closed position or in preventing the choke valve from being moved from its fully opened positioned to a closed position. In either instance, starting problems and/or poor fuel economy can result. With previous mechanisms, the operator has had to move to the engine compartment and manually position the choke valve through operating either the linkage or the choke valve itself. As a result, it is required to have another person handy in order to crank the engine or start the engine while the first person holds the choke valve in the desired position. Obviously, this is not at all advantageous.
There have also been provided so called "unloader mechanisms" that permit the operator to hold a stuck choke valve in a partially opened position to facilitate starting. However, these mechanisms have necessitated holding the throttle valve in a fully opened position and this is not always the optimum position for starting. Furthermore, the choke valve may again move to its closed position once the throttle valve is moved away from its fully opened position.
It is, therefore, a principal object of this invention to provide an improved device for manually operating an automatic choke mechanism.
It is another object of this invention to provide an automatic operator for an automatic choke mechanism with a manual override that will permit the choke to function normally in the automatic mode or be positioned manually at the operator's control.